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            <div><h4 class="title">
                <a name="asio.reference.read_until.overload15"></a><a class="link" href="overload15.html"
                                                                      title="read_until (15 of 24 overloads)">read_until
                (15
                of 24 overloads)</a>
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    <p>
        Read data into a streambuf until a function object indicates a match.
    </p>
    <pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span>
    <span class="keyword">typename</span> <a class="link" href="../SyncReadStream.html"
                                             title="Buffer-oriented synchronous read stream requirements">SyncReadStream</a><span
                class="special">,</span>
    <span class="keyword">typename</span> <span class="identifier">Allocator</span><span class="special">,</span>
    <span class="keyword">typename</span> <span class="identifier">MatchCondition</span><span
                class="special">&gt;</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span
                class="identifier">read_until</span><span class="special">(</span>
    <span class="identifier">SyncReadStream</span> <span class="special">&amp;</span> <span
                class="identifier">s</span><span class="special">,</span>
    <span class="identifier">asio</span><span class="special">::</span><span
                class="identifier">basic_streambuf</span><span class="special">&lt;</span> <span class="identifier">Allocator</span> <span
                class="special">&gt;</span> <span class="special">&amp;</span> <span class="identifier">b</span><span
                class="special">,</span>
    <span class="identifier">MatchCondition</span> <span class="identifier">match_condition</span><span class="special">,</span>
    <span class="keyword">typename</span> <span class="identifier">constraint</span><span
                class="special">&lt;</span> <span class="identifier">is_match_condition</span><span
                class="special">&lt;</span> <span class="identifier">MatchCondition</span> <span
                class="special">&gt;::</span><span class="identifier">value</span> <span
                class="special">&gt;::</span><span class="identifier">type</span>  <span class="special">=</span> <span
                class="number">0</span><span class="special">);</span>
</pre>
    <p>
        This function is used to read data into the specified streambuf until a
        user-defined match condition function object, when applied to the data
        contained in the streambuf, indicates a successful match. The call will
        block until one of the following conditions is true:
    </p>
    <div class="itemizedlist">
        <ul class="itemizedlist" type="disc">
            <li class="listitem">
                The match condition function object returns a std::pair where the second
                element evaluates to true.
            </li>
            <li class="listitem">
                An error occurred.
            </li>
        </ul>
    </div>
    <p>
        This operation is implemented in terms of zero or more calls to the stream's
        read_some function. If the match condition function object already indicates
        a match, the function returns immediately.
    </p>
    <h6>
        <a name="asio.reference.read_until.overload15.h0"></a>
        <span><a name="asio.reference.read_until.overload15.parameters"></a></span><a class="link"
                                                                                      href="overload15.html#asio.reference.read_until.overload15.parameters">Parameters</a>
    </h6>
    <div class="variablelist">
        <p class="title"><b></b></p>
        <dl>
            <dt><span class="term">s</span></dt>
            <dd><p>
                The stream from which the data is to be read. The type must support
                the SyncReadStream concept.
            </p></dd>
            <dt><span class="term">b</span></dt>
            <dd><p>
                A streambuf object into which the data will be read.
            </p></dd>
            <dt><span class="term">match_condition</span></dt>
            <dd>
                <p>
                    The function object to be called to determine whether a match exists.
                    The signature of the function object must be:
                </p>
                <pre class="programlisting"><span class="identifier">pair</span><span class="special">&lt;</span><span
                        class="identifier">iterator</span><span class="special">,</span> <span
                        class="keyword">bool</span><span class="special">&gt;</span> <span class="identifier">match_condition</span><span
                        class="special">(</span><span class="identifier">iterator</span> <span
                        class="identifier">begin</span><span class="special">,</span> <span
                        class="identifier">iterator</span> <span class="identifier">end</span><span
                        class="special">);</span>
</pre>
                <p>
                    where <code class="computeroutput"><span class="identifier">iterator</span></code> represents
                    the type:
                </p>
                <pre class="programlisting"><span class="identifier">buffers_iterator</span><span
                        class="special">&lt;</span><span class="identifier">basic_streambuf</span><span class="special">&lt;</span><span
                        class="identifier">Allocator</span><span class="special">&gt;::</span><span class="identifier">const_buffers_type</span><span
                        class="special">&gt;</span>
</pre>
                <p>
                    The iterator parameters <code class="computeroutput"><span class="identifier">begin</span></code>
                    and <code class="computeroutput"><span class="identifier">end</span></code> define the
                    range of bytes to be scanned to determine whether there is a match.
                    The <code class="computeroutput"><span class="identifier">first</span></code> member
                    of the return value is an iterator marking one-past-the-end of the
                    bytes that have been consumed by the match function. This iterator
                    is used to calculate the <code class="computeroutput"><span class="identifier">begin</span></code>
                    parameter for any subsequent invocation of the match condition. The
                    <code class="computeroutput"><span class="identifier">second</span></code> member of
                    the return value is true if a match has been found, false otherwise.
                </p>
            </dd>
        </dl>
    </div>
    <h6>
        <a name="asio.reference.read_until.overload15.h1"></a>
        <span><a name="asio.reference.read_until.overload15.return_value"></a></span><a class="link"
                                                                                        href="overload15.html#asio.reference.read_until.overload15.return_value">Return
        Value</a>
    </h6>
    <p>
        The number of bytes in the streambuf's get area that have been fully consumed
        by the match function.
    </p>
    <h6>
        <a name="asio.reference.read_until.overload15.h2"></a>
        <span><a name="asio.reference.read_until.overload15.exceptions"></a></span><a class="link"
                                                                                      href="overload15.html#asio.reference.read_until.overload15.exceptions">Exceptions</a>
    </h6>
    <div class="variablelist">
        <p class="title"><b></b></p>
        <dl>
            <dt><span class="term">asio::system_error</span></dt>
            <dd><p>
                Thrown on failure.
            </p></dd>
        </dl>
    </div>
    <h6>
        <a name="asio.reference.read_until.overload15.h3"></a>
        <span><a name="asio.reference.read_until.overload15.remarks"></a></span><a class="link"
                                                                                   href="overload15.html#asio.reference.read_until.overload15.remarks">Remarks</a>
    </h6>
    <p>
        After a successful read_until operation, the streambuf may contain additional
        data beyond that which matched the function object. An application will
        typically leave that data in the streambuf for a subsequent read_until
        operation to examine.
    </p>
    <p>
        The default implementation of the <code class="computeroutput"><span
            class="identifier">is_match_condition</span></code>
        type trait evaluates to true for function pointers and function objects
        with a <code class="computeroutput"><span class="identifier">result_type</span></code> typedef.
        It must be specialised for other user-defined function objects.
    </p>
    <h6>
        <a name="asio.reference.read_until.overload15.h4"></a>
        <span><a name="asio.reference.read_until.overload15.examples"></a></span><a class="link"
                                                                                    href="overload15.html#asio.reference.read_until.overload15.examples">Examples</a>
    </h6>
    <p>
        To read data into a streambuf until whitespace is encountered:
    </p>
    <pre class="programlisting"><span class="keyword">typedef</span> <span class="identifier">asio</span><span
            class="special">::</span><span class="identifier">buffers_iterator</span><span class="special">&lt;</span>
    <span class="identifier">asio</span><span class="special">::</span><span class="identifier">streambuf</span><span
                class="special">::</span><span class="identifier">const_buffers_type</span><span
                class="special">&gt;</span> <span class="identifier">iterator</span><span class="special">;</span>

<span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span
                class="special">&lt;</span><span class="identifier">iterator</span><span class="special">,</span> <span
                class="keyword">bool</span><span class="special">&gt;</span>
<span class="identifier">match_whitespace</span><span class="special">(</span><span
                class="identifier">iterator</span> <span class="identifier">begin</span><span
                class="special">,</span> <span class="identifier">iterator</span> <span
                class="identifier">end</span><span class="special">)</span>
<span class="special">{</span>
  <span class="identifier">iterator</span> <span class="identifier">i</span> <span class="special">=</span> <span
                class="identifier">begin</span><span class="special">;</span>
  <span class="keyword">while</span> <span class="special">(</span><span class="identifier">i</span> <span
                class="special">!=</span> <span class="identifier">end</span><span class="special">)</span>
    <span class="keyword">if</span> <span class="special">(</span><span class="identifier">std</span><span
                class="special">::</span><span class="identifier">isspace</span><span class="special">(*</span><span
                class="identifier">i</span><span class="special">++))</span>
      <span class="keyword">return</span> <span class="identifier">std</span><span class="special">::</span><span
                class="identifier">make_pair</span><span class="special">(</span><span class="identifier">i</span><span
                class="special">,</span> <span class="keyword">true</span><span class="special">);</span>
  <span class="keyword">return</span> <span class="identifier">std</span><span class="special">::</span><span
                class="identifier">make_pair</span><span class="special">(</span><span class="identifier">i</span><span
                class="special">,</span> <span class="keyword">false</span><span class="special">);</span>
<span class="special">}</span>
<span class="special">...</span>
<span class="identifier">asio</span><span class="special">::</span><span class="identifier">streambuf</span> <span
                class="identifier">b</span><span class="special">;</span>
<span class="identifier">asio</span><span class="special">::</span><span class="identifier">read_until</span><span
                class="special">(</span><span class="identifier">s</span><span class="special">,</span> <span
                class="identifier">b</span><span class="special">,</span> <span
                class="identifier">match_whitespace</span><span class="special">);</span>
</pre>
    <p>
        To read data into a streambuf until a matching character is found:
    </p>
    <pre class="programlisting"><span class="keyword">class</span> <span class="identifier">match_char</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
  <span class="keyword">explicit</span> <span class="identifier">match_char</span><span class="special">(</span><span
                class="keyword">char</span> <span class="identifier">c</span><span class="special">)</span> <span
                class="special">:</span> <span class="identifier">c_</span><span class="special">(</span><span
                class="identifier">c</span><span class="special">)</span> <span class="special">{}</span>

  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span
                class="identifier">Iterator</span><span class="special">&gt;</span>
  <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span
                class="special">&lt;</span><span class="identifier">Iterator</span><span class="special">,</span> <span
                class="keyword">bool</span><span class="special">&gt;</span> <span class="keyword">operator</span><span
                class="special">()(</span>
      <span class="identifier">Iterator</span> <span class="identifier">begin</span><span class="special">,</span> <span
                class="identifier">Iterator</span> <span class="identifier">end</span><span
                class="special">)</span> <span class="keyword">const</span>
  <span class="special">{</span>
    <span class="identifier">Iterator</span> <span class="identifier">i</span> <span class="special">=</span> <span
                class="identifier">begin</span><span class="special">;</span>
    <span class="keyword">while</span> <span class="special">(</span><span class="identifier">i</span> <span
                class="special">!=</span> <span class="identifier">end</span><span class="special">)</span>
      <span class="keyword">if</span> <span class="special">(</span><span class="identifier">c_</span> <span
                class="special">==</span> <span class="special">*</span><span class="identifier">i</span><span
                class="special">++)</span>
        <span class="keyword">return</span> <span class="identifier">std</span><span class="special">::</span><span
                class="identifier">make_pair</span><span class="special">(</span><span class="identifier">i</span><span
                class="special">,</span> <span class="keyword">true</span><span class="special">);</span>
    <span class="keyword">return</span> <span class="identifier">std</span><span class="special">::</span><span
                class="identifier">make_pair</span><span class="special">(</span><span class="identifier">i</span><span
                class="special">,</span> <span class="keyword">false</span><span class="special">);</span>
  <span class="special">}</span>

<span class="keyword">private</span><span class="special">:</span>
  <span class="keyword">char</span> <span class="identifier">c_</span><span class="special">;</span>
<span class="special">};</span>

<span class="keyword">namespace</span> <span class="identifier">asio</span> <span class="special">{</span>
  <span class="keyword">template</span> <span class="special">&lt;&gt;</span> <span class="keyword">struct</span> <span
                class="identifier">is_match_condition</span><span class="special">&lt;</span><span class="identifier">match_char</span><span
                class="special">&gt;</span>
    <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">boost</span><span
                class="special">::</span><span class="identifier">true_type</span> <span class="special">{};</span>
<span class="special">}</span> <span class="comment">// namespace asio</span>
<span class="special">...</span>
<span class="identifier">asio</span><span class="special">::</span><span class="identifier">streambuf</span> <span
                class="identifier">b</span><span class="special">;</span>
<span class="identifier">asio</span><span class="special">::</span><span class="identifier">read_until</span><span
                class="special">(</span><span class="identifier">s</span><span class="special">,</span> <span
                class="identifier">b</span><span class="special">,</span> <span
                class="identifier">match_char</span><span class="special">(</span><span class="char">'a'</span><span
                class="special">));</span>
</pre>
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                Distributed under the Boost Software License, Version 1.0. (See accompanying
                file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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